"Organic Solar Cells Coming To A Roof Near You"

Image Inexpensive solar cells, vastly improved medical imaging techniques
and lighter and more flexible television screens are among the
potential applications envisioned for organic electronics. Yes, that means that soon you could have a solar powered TV or even a solar x-ray machine at the local hospital. (Hopefuly your bill will go down with their power costs)

Recent
experiments conducted by Greg Scholes and Elisabetta Collini of
University of Toronto's Department of Chemistry may bring these within
closer by provding more information on the way molecules absorb and
move energy. These findings were published inl journal Science on January 16.

The U of T
team looked specifically at conjugated
polymers which are believed to be one of the most promising candidates
for building efficient organic solar cells.

What exactly is a conjugated
polymer anyway?

I know, it is not exactly a household name and most of us need the introduction. Conjugated
polymers are very long organic molecules that possess properties like
those of semiconductors and so can be used to make transistors and
LEDs. When these conductive polymers absorb light, the energy moves
along and among the polymer chains before it is converted to electrical
charges.

"One of the biggest obstacles to organic solar cells
is that it is difficult to control what happens after light is
absorbed: whether the desired property is transmitting energy, storing
information or emitting light," explains Collini. "Our experiment
suggests it is possible to achieve control using quantum effects, even
under relatively normal conditions."

"We found that the
ultrafast movement of energy through and between molecules happens by a
quantum-mechanical mechanism rather than through random hopping, even
at room temperature," explains Scholes. "This is extraordinary and will
greatly influence future work in the field because everyone thought
that these kinds of quantum effects could only operate in complex
systems at very low temperatures," he says.

This discovery opens the way to designing organic solar cells or
sensors that capture light and transfer its energy much more
effectively. It also has significant implications for quantum computing
because it suggests that quantum information may survive significantly
longer than previously believed.

These experiments consist of the use of ultrashort laser pulses to put the conjugated polymer
into a quantum-mechanical state, whereby it is simultaneously in the
ground (normal) state and a state where light has been absorbed. This
is called a superposition state or quantum coherence. Then they used a
sophisticated method involving more ultrashort laser pulses to observe
whether this quantum state can migrate along or between polymer chains. It turns out that they can, to a limited extent.

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